A standard motor-vehicle door latch has a latch housing mounted on a door edge, a latch fork pivotal on the housing and latchingly engageable around a doorpost-mounted lock bolt, and a lock pawl mounted on the housing for retaining the fork latched around the bolt or releasing it to free the bolt. This pawl can be moved into the fork-freeing position by inside and outside door handles, and the outside handle at least can be decoupled from the pawl by locking mechanisms inside and outside the door.
Typically the outside handle is pulled out to open the door, as such movement makes pulling the door open a natural extension of the unlatching operation. To this end a lever linkage is provided that couples the outside door handle to the lock pawl.
Even in a good mass-production operation the thickness of the vehicle door, that is the horizontal distance between the inside and outside door panels, can vary considerably. In order to compensate for these variations in thickness tolerance, it is therefore standard to make the outside door handle travel through a considerable stroke through part of which it is effective to act on the lock pawl through the above-mentioned lever linkage. Not only does this make for sloppy lock action, but the force that resists movement of the outside door handle varies considerably over its stroke, being considerably more during the short portion of this stroke that the unlatching work is actually done.
It has been suggested to provide complicated adjustment capabilities in the door latch in order to avoid this problem. All such provisions, however, make for considerable installation work for the door latch. Skilled personnel must carry out specialized adjustment operations on each latch, thereby increasing production costs. Furthermore any misadjustment is frequently discovered only after the door is fully assembled, so that it must be taken apart for readjustment.